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Commit 5befdc38 authored by Takuya Yoshikawa's avatar Takuya Yoshikawa Committed by Paolo Bonzini
Browse files

KVM: Simplify kvm->tlbs_dirty handling 



When this was introduced, kvm_flush_remote_tlbs() could be called
without holding mmu_lock.  It is now acknowledged that the function
must be called before releasing mmu_lock, and all callers have already
been changed to do so.

There is no need to use smp_mb() and cmpxchg() any more.

Signed-off-by: default avatarTakuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent f18eb31f

arch/x86/kvm/paging_tmpl.h

+4 −3
Original line number Diff line number Diff line
@@ -913,7 +913,8 @@ static gpa_t FNAME(gva_to_gpa_nested)(struct kvm_vcpu *vcpu, gva_t vaddr, 
 *   and kvm_mmu_notifier_invalidate_range_start detect the mapping page isn't

 *   used by guest then tlbs are not flushed, so guest is allowed to access the

 *   freed pages.

 *   And we increase kvm->tlbs_dirty to delay tlbs flush in this case.

 *   We set tlbs_dirty to let the notifier know this change and delay the flush

 *   until such a case actually happens.

 */

static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)

{
@@ -942,7 +943,7 @@ static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp) 
			return -EINVAL;



		if (FNAME(prefetch_invalid_gpte)(vcpu, sp, &sp->spt[i], gpte)) {

			vcpu->kvm->tlbs_dirty++;

			vcpu->kvm->tlbs_dirty = true;

			continue;

		}
@@ -957,7 +958,7 @@ static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp) 


		if (gfn != sp->gfns[i]) {

			drop_spte(vcpu->kvm, &sp->spt[i]);

			vcpu->kvm->tlbs_dirty++;

			vcpu->kvm->tlbs_dirty = true;

			continue;

		}

include/linux/kvm_host.h

+3 −1
Original line number Diff line number Diff line
@@ -401,7 +401,9 @@ struct kvm { 
	unsigned long mmu_notifier_seq;

	long mmu_notifier_count;

#endif

	long tlbs_dirty;

	/* Protected by mmu_lock */

	bool tlbs_dirty;



	struct list_head devices;

};

virt/kvm/kvm_main.c

+1 −4
Original line number Diff line number Diff line
@@ -186,12 +186,9 @@ static bool make_all_cpus_request(struct kvm *kvm, unsigned int req) 


void kvm_flush_remote_tlbs(struct kvm *kvm)

{

	long dirty_count = kvm->tlbs_dirty;



	smp_mb();

	if (make_all_cpus_request(kvm, KVM_REQ_TLB_FLUSH))

		++kvm->stat.remote_tlb_flush;

	cmpxchg(&kvm->tlbs_dirty, dirty_count, 0);

	kvm->tlbs_dirty = false;

}

EXPORT_SYMBOL_GPL(kvm_flush_remote_tlbs);